How Does Mechanical Doping Work?

Cyclocross racer Femke van den Driessche has become famous, and put bike racing in the news, for all the wrong reasons. The Belgian athlete has the dubious distinction of being the first rider accused of “technological fraud,” or mechanical doping, after a hidden motor was discovered in one of her spare bikes at the 2016 UCI Cyclocross World Championships.

Rumors and serious accusations of racers using hidden motor systems have been around the sport since 2010, when Fabian Cancellara accelerated away from the field to win the Tour of Flanders, and Italian journalist and ex-pro Davide Cassani later demonstrated a system for RAI TV.

But what is mechanical doping? How does it work? And is it really a major problem?

E-bikes are not exactly new, but most of the time they’re readily recognizable with large motors and battery systems. The hidden versions are far more subtle. The most popular and widely known is from German company Vivax Assist; it’s small enough to go unnoticed on a normal road bike, but powerful enough to change a race.

The Vivax Assist system requires a careful retrofit to an existing frame. The crankset’s bottom bracket spindle is fitted with a notch-toothed gear ring. A cylindrical electric motor, inserted in the seat tube, has a splined drive gear that meshes perpendicularly with the teeth on the BB ring. A horizontal hole is drilled in the seat tube for a fixing pin, so the motor doesn’t just spin inside the tube. Careful patching would be necessary to conceal the hole, and a minimum seat-tube diameter (30.9mm) is required, which rules out some bikes.

A wiring system runs to a remote on-off button concealed under the handlebar tape, which could be retrofitted to a remote shifter button. On the normal Vivax Assist system, the battery sits in a seatpack or water bottle. Either might be noticeable to keen eyes, but if a rider is willing to sacrifice some power or run time, a smaller battery could be concealed inside the frame. That would also reduce total system weight from the 1.8 kilograms (3.96 pounds) Vivax claims for its standard setup.

The Vivax Assist conceals the entire motor inside the seat tube. The standard systems use external batteries, but smaller ones could also be hidden inside the bike.

Vivax

But is that weight worth it? It depends. In a hidden system like this, the battery isn’t large enough to provide power for an entire road race, although it could for most of a cyclocross race, which runs an hour for elite men and 45 minutes for elite women. Most of the time, it would be up to the rider to decide when to turn the system on and off—for crucial climbs or attacks, for instance. The systems are said to be very quiet—possibly undetectable against crowd noise or even nearby cars and motorcycles in the race caravan.

Vivax claims its stock system provides 200 watts of additional power to the crankshaft, but due to efficiency losses, actual power at the wheel is anywhere from 40 to 100 additional watts depending on the rider’s own cadence. Burn time is 40 to 100 minutes, according to Vivax’s charts. At slower cadences, the motor helps more than it does at faster RPMs. Depending on the version, once above 75 or 90 RPM, the power assist drops dramatically because the rider’s own pedaling rate is faster than the motor’s.

That’s for the stock system; a custom system could be tuned to work at higher cadences, or to provide power over a shorter period of time. Even a modest boost of 20 to 30 watts could make a significant difference on a long climb in a stage race like the Tour de France.

But all of that is freely available information. The question, for years, has been simple: Is anyone actually using these things in races? Until Saturday, there were rumors and accusations, but no proof. Van den Driessche and her father deny any intent to cheat and say that the situation was a mix-up: A friend’s bike outfitted with a motor was mistakenly brought to the pits. Van den Driessche never rode the bike, which was confiscated from the pits after just one lap of the U23 women’s race in which van den Driessche competed.

If true, that’s a monumental screwup on the part of the Belgian team staff. But it should be easily proved false. The bike was apparently a team model, and if factors like fit and ID stickers prove out that it is in fact van den Dreissche’s bike, then the alibi may be exposed as a ruse.

What’s not in dispute: That, for the first time, a motorized bike was found, and at a World Championship race no less. The UCI in the past has relied on some cumbersome tactics to screen bikes, including a large X-ray machine, or physically disassembling the bottom bracket area. By accounts from the World Championships, they have new, more portable technology available.

The UCI has sporadically screened bikes in the past; there was criticism at last year’s Tour de France that only one percent of bikes were screened, despite what some observers felt were curious and excessive bike changes during key stages by some top racers like Alberto Contador. No motors were found, which led other observers to criticize the UCI’s efforts as useless distraction.

Whatever the case, the UCI may now step up its efforts in road racing. The penalty for technological fraud is significant in some ways and less so in others. Bans start at six months, which may be too short for a kind of cheating that goes straight to the heart of bike racing as an inherently human-powered sport. But—partly because it would be almost impossible for a rider to cheat like this on his own, without team knowledge—the ban also can apply to a rider’s entire team, essentially creating a death sentence for any pro cycling team found to employ motors.

Whether the UCI will catch more cheaters remains to be seen. Right now, there are only two certainties: A new form of cheating is technologically possible, and more than just theory.

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